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| Titel |
Climatology of Vb cyclones, physical mechanisms and their impact on extreme precipitation over Central Europe |
| VerfasserIn |
M. Messmer, J. J. Gómez-Navarro, C. C. Raible |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
2190-4979
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| Digitales Dokument |
URL |
| Erschienen |
In: Earth System Dynamics ; 6, no. 2 ; Nr. 6, no. 2 (2015-09-01), S.541-553 |
| Datensatznummer |
250115475
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| Publikation (Nr.) |
 copernicus.org/esd-6-541-2015.pdf |
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| Zusammenfassung |
| Cyclones, which develop over the western Mediterranean and move northeastward
are a major source of extreme weather and known to be responsible for heavy
precipitation over the northern side of the Alpine range and Central Europe.
As the relevant processes triggering these so-called Vb events and their
impact on extreme precipitation are not yet fully understood, this study
focuses on gaining insight into the dynamics of past events. For this, a
cyclone detection and tracking tool is applied to the ERA-Interim reanalysis
(1979–2013) to identify prominent Vb situations. Precipitation in the
ERA-Interim and the E-OBS data sets is used to evaluate case-to-case
precipitation amounts and to assess consistency between the two data sets.
Both data sets exhibit high variability in precipitation amounts among
different Vb events. While only 23 % of all Vb events are associated with
extreme precipitation, around 15 % of all extreme precipitation days
(99 percentile) over the northern Alpine region and Central Europe are
induced by Vb events, although Vb cyclones are rare events (2.3 per year). To
obtain a better understanding of the variability within Vb events, the
analysis of the 10 heaviest and lowest precipitation Vb events reveals
noticeable differences in the state of the atmosphere. These differences are
most pronounced in the geopotential height and potential vorticity field,
indicating a much stronger cyclone for heavy precipitation events. The
related differences in wind direction are responsible for the moisture
transport around the Alps and the orographical lifting along the northern
slopes of the Alps. These effects are the main reasons for a disastrous
outcome of Vb events, and consequently are absent in the Vb events associated
with low precipitation. Hence, our results point out that heavy precipitation
related to Vb events is mainly related to large-scale dynamics rather than to
thermodynamic processes. |
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